/*
 * Copyright 2002-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.util;

import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * PathMatcher implementation for Ant-style path patterns. Examples are provided below.
 *
 * <p>Part of this mapping code has been kindly borrowed from <a href="http://ant.apache.org">Apache Ant</a>.
 *
 * <p>The mapping matches URLs using the following rules:<br> <ul> <li>? matches one character</li> <li>* matches zero
 * or more characters</li> <li>** matches zero or more 'directories' in a path</li> </ul>
 *
 * <p>Some examples:<br> <ul> <li><code>com/t?st.jsp</code> - matches <code>com/test.jsp</code> but also
 * <code>com/tast.jsp</code> or <code>com/txst.jsp</code></li> <li><code>com/*.jsp</code> - matches all
 * <code>.jsp</code> files in the <code>com</code> directory</li> <li><code>com/&#42;&#42;/test.jsp</code> - matches all
 * <code>test.jsp</code> files underneath the <code>com</code> path</li> <li><code>org/springframework/&#42;&#42;/*.jsp</code>
 * - matches all <code>.jsp</code> files underneath the <code>org/springframework</code> path</li>
 * <li><code>org/&#42;&#42;/servlet/bla.jsp</code> - matches <code>org/springframework/servlet/bla.jsp</code> but also
 * <code>org/springframework/testing/servlet/bla.jsp</code> and <code>org/servlet/bla.jsp</code></li> </ul>
 *
 * @author Alef Arendsen
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @author Arjen Poutsma
 * @since 16.07.2003
 */
public class AntPathMatcher implements PathMatcher {

   private static final Pattern VARIABLE_PATTERN = Pattern.compile("\\{[^/]+?\\}");

   /** Default path separator: "/" */
   public static final String DEFAULT_PATH_SEPARATOR = "/";

   private String pathSeparator = DEFAULT_PATH_SEPARATOR;


   /** Set the path separator to use for pattern parsing. Default is "/", as in Ant. */
   public void setPathSeparator(String pathSeparator) {
      this.pathSeparator = (pathSeparator != null ? pathSeparator : DEFAULT_PATH_SEPARATOR);
   }


   public boolean isPattern(String path) {
      return (path.indexOf('*') != -1 || path.indexOf('?') != -1);
   }

   public boolean match(String pattern, String path) {
      return doMatch(pattern, path, true, null);
   }

   public boolean matchStart(String pattern, String path) {
      return doMatch(pattern, path, false, null);
   }


   /**
    * Actually match the given <code>path</code> against the given <code>pattern</code>.
    * @param pattern the pattern to match against
    * @param path the path String to test
    * @param fullMatch whether a full pattern match is required (else a pattern match
    * as far as the given base path goes is sufficient)
    * @return <code>true</code> if the supplied <code>path</code> matched, <code>false</code> if it didn't
    */
   protected boolean doMatch(String pattern, String path, boolean fullMatch,
         Map<String, String> uriTemplateVariables) {

      if (path.startsWith(this.pathSeparator) != pattern.startsWith(this.pathSeparator)) {
         return false;
      }

      String[] pattDirs = StringUtils.tokenizeToStringArray(pattern, this.pathSeparator);
      String[] pathDirs = StringUtils.tokenizeToStringArray(path, this.pathSeparator);

      int pattIdxStart = 0;
      int pattIdxEnd = pattDirs.length - 1;
      int pathIdxStart = 0;
      int pathIdxEnd = pathDirs.length - 1;

      // Match all elements up to the first **
      while (pattIdxStart <= pattIdxEnd && pathIdxStart <= pathIdxEnd) {
         String patDir = pattDirs[pattIdxStart];
         if ("**".equals(patDir)) {
            break;
         }
         if (!matchStrings(patDir, pathDirs[pathIdxStart], uriTemplateVariables)) {
            return false;
         }
         pattIdxStart++;
         pathIdxStart++;
      }

      if (pathIdxStart > pathIdxEnd) {
         // Path is exhausted, only match if rest of pattern is * or **'s
         if (pattIdxStart > pattIdxEnd) {
            return (pattern.endsWith(this.pathSeparator) ? path.endsWith(this.pathSeparator) :
                  !path.endsWith(this.pathSeparator));
         }
         if (!fullMatch) {
            return true;
         }
         if (pattIdxStart == pattIdxEnd && pattDirs[pattIdxStart].equals("*") && path.endsWith(this.pathSeparator)) {
            return true;
         }
         for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
            if (!pattDirs[i].equals("**")) {
               return false;
            }
         }
         return true;
      }
      else if (pattIdxStart > pattIdxEnd) {
         // String not exhausted, but pattern is. Failure.
         return false;
      }
      else if (!fullMatch && "**".equals(pattDirs[pattIdxStart])) {
         // Path start definitely matches due to "**" part in pattern.
         return true;
      }

      // up to last '**'
      while (pattIdxStart <= pattIdxEnd && pathIdxStart <= pathIdxEnd) {
         String patDir = pattDirs[pattIdxEnd];
         if (patDir.equals("**")) {
            break;
         }
         if (!matchStrings(patDir, pathDirs[pathIdxEnd], uriTemplateVariables)) {
            return false;
         }
         pattIdxEnd--;
         pathIdxEnd--;
      }
      if (pathIdxStart > pathIdxEnd) {
         // String is exhausted
         for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
            if (!pattDirs[i].equals("**")) {
               return false;
            }
         }
         return true;
      }

      while (pattIdxStart != pattIdxEnd && pathIdxStart <= pathIdxEnd) {
         int patIdxTmp = -1;
         for (int i = pattIdxStart + 1; i <= pattIdxEnd; i++) {
            if (pattDirs[i].equals("**")) {
               patIdxTmp = i;
               break;
            }
         }
         if (patIdxTmp == pattIdxStart + 1) {
            // '**/**' situation, so skip one
            pattIdxStart++;
            continue;
         }
         // Find the pattern between padIdxStart & padIdxTmp in str between
         // strIdxStart & strIdxEnd
         int patLength = (patIdxTmp - pattIdxStart - 1);
         int strLength = (pathIdxEnd - pathIdxStart + 1);
         int foundIdx = -1;

         strLoop:
         for (int i = 0; i <= strLength - patLength; i++) {
            for (int j = 0; j < patLength; j++) {
               String subPat = pattDirs[pattIdxStart + j + 1];
               String subStr = pathDirs[pathIdxStart + i + j];
               if (!matchStrings(subPat, subStr, uriTemplateVariables)) {
                  continue strLoop;
               }
            }
            foundIdx = pathIdxStart + i;
            break;
         }

         if (foundIdx == -1) {
            return false;
         }

         pattIdxStart = patIdxTmp;
         pathIdxStart = foundIdx + patLength;
      }

      for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
         if (!pattDirs[i].equals("**")) {
            return false;
         }
      }

      return true;
   }

   /**
    * Tests whether or not a string matches against a pattern. The pattern may contain two special characters:<br> '*'
    * means zero or more characters<br> '?' means one and only one character
    * @param pattern pattern to match against. Must not be <code>null</code>.
    * @param str string which must be matched against the pattern. Must not be <code>null</code>.
    * @return <code>true</code> if the string matches against the pattern, or <code>false</code> otherwise.
    */
   private boolean matchStrings(String pattern, String str, Map<String, String> uriTemplateVariables) {
      AntPathStringMatcher matcher = new AntPathStringMatcher(pattern, str, uriTemplateVariables);
      return matcher.matchStrings();
   }

   /**
    * Given a pattern and a full path, determine the pattern-mapped part. <p>For example: <ul>
    * <li>'<code>/docs/cvs/commit.html</code>' and '<code>/docs/cvs/commit.html</code> -> ''</li>
    * <li>'<code>/docs/*</code>' and '<code>/docs/cvs/commit</code> -> '<code>cvs/commit</code>'</li>
    * <li>'<code>/docs/cvs/*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>commit.html</code>'</li>
    * <li>'<code>/docs/**</code>' and '<code>/docs/cvs/commit</code> -> '<code>cvs/commit</code>'</li>
    * <li>'<code>/docs/**\/*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>cvs/commit.html</code>'</li>
    * <li>'<code>/*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>docs/cvs/commit.html</code>'</li>
    * <li>'<code>*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>/docs/cvs/commit.html</code>'</li>
    * <li>'<code>*</code>' and '<code>/docs/cvs/commit.html</code> -> '<code>/docs/cvs/commit.html</code>'</li> </ul>
    * <p>Assumes that {@link #match} returns <code>true</code> for '<code>pattern</code>' and '<code>path</code>', but
    * does <strong>not</strong> enforce this.
    */
   public String extractPathWithinPattern(String pattern, String path) {
      String[] patternParts = StringUtils.tokenizeToStringArray(pattern, this.pathSeparator);
      String[] pathParts = StringUtils.tokenizeToStringArray(path, this.pathSeparator);

      StringBuilder builder = new StringBuilder();

      // Add any path parts that have a wildcarded pattern part.
      int puts = 0;
      for (int i = 0; i < patternParts.length; i++) {
         String patternPart = patternParts[i];
         if ((patternPart.indexOf('*') > -1 || patternPart.indexOf('?') > -1) && pathParts.length >= i + 1) {
            if (puts > 0 || (i == 0 && !pattern.startsWith(this.pathSeparator))) {
               builder.append(this.pathSeparator);
            }
            builder.append(pathParts[i]);
            puts++;
         }
      }

      // Append any trailing path parts.
      for (int i = patternParts.length; i < pathParts.length; i++) {
         if (puts > 0 || i > 0) {
            builder.append(this.pathSeparator);
         }
         builder.append(pathParts[i]);
      }

      return builder.toString();
   }

   public Map<String, String> extractUriTemplateVariables(String pattern, String path) {
      Map<String, String> variables = new LinkedHashMap<String, String>();
      boolean result = doMatch(pattern, path, true, variables);
//      Assert.state(result, "Pattern \"" + pattern + "\" is not a match for \"" + path + "\"");
      return variables;
   }

   /**
    * Combines two patterns into a new pattern that is returned.
    * <p>This implementation simply concatenates the two patterns, unless the first pattern
    * contains a file extension match (such as {@code *.html}. In that case, the second pattern
    * should be included in the first, or an {@code IllegalArgumentException} is thrown.
    * <p>For example: <table>
    * <tr><th>Pattern 1</th><th>Pattern 2</th><th>Result</th></tr> <tr><td>/hotels</td><td>{@code
    * null}</td><td>/hotels</td></tr> <tr><td>{@code null}</td><td>/hotels</td><td>/hotels</td></tr>
    * <tr><td>/hotels</td><td>/bookings</td><td>/hotels/bookings</td></tr> <tr><td>/hotels</td><td>bookings</td><td>/hotels/bookings</td></tr>
    * <tr><td>/hotels/*</td><td>/bookings</td><td>/hotels/bookings</td></tr> <tr><td>/hotels/&#42;&#42;</td><td>/bookings</td><td>/hotels/&#42;&#42;/bookings</td></tr>
    * <tr><td>/hotels</td><td>{hotel}</td><td>/hotels/{hotel}</td></tr> <tr><td>/hotels/*</td><td>{hotel}</td><td>/hotels/{hotel}</td></tr>
    * <tr><td>/hotels/&#42;&#42;</td><td>{hotel}</td><td>/hotels/&#42;&#42;/{hotel}</td></tr>
    * <tr><td>/*.html</td><td>/hotels.html</td><td>/hotels.html</td></tr> <tr><td>/*.html</td><td>/hotels</td><td>/hotels.html</td></tr>
    * <tr><td>/*.html</td><td>/*.txt</td><td>IllegalArgumentException</td></tr> </table>
    * @param pattern1 the first pattern
    * @param pattern2 the second pattern
    * @return the combination of the two patterns
    * @throws IllegalArgumentException when the two patterns cannot be combined
    */
   public String combine(String pattern1, String pattern2) {
      if (!StringUtils.hasText(pattern1) && !StringUtils.hasText(pattern2)) {
         return "";
      }
      else if (!StringUtils.hasText(pattern1)) {
         return pattern2;
      }
      else if (!StringUtils.hasText(pattern2)) {
         return pattern1;
      }
      else if (match(pattern1, pattern2)) {
         return pattern2;
      }
      else if (pattern1.endsWith("/*")) {
         if (pattern2.startsWith("/")) {
            // /hotels/* + /booking -> /hotels/booking
            return pattern1.substring(0, pattern1.length() - 1) + pattern2.substring(1);
         }
         else {
            // /hotels/* + booking -> /hotels/booking
            return pattern1.substring(0, pattern1.length() - 1) + pattern2;
         }
      }
      else if (pattern1.endsWith("/**")) {
         if (pattern2.startsWith("/")) {
            // /hotels/** + /booking -> /hotels/**/booking
            return pattern1 + pattern2;
         }
         else {
            // /hotels/** + booking -> /hotels/**/booking
            return pattern1 + "/" + pattern2;
         }
      }
      else {
         int dotPos1 = pattern1.indexOf('.');
         if (dotPos1 == -1) {
            // simply concatenate the two patterns
            if (pattern1.endsWith("/") || pattern2.startsWith("/")) {
               return pattern1 + pattern2;
            }
            else {
               return pattern1 + "/" + pattern2;
            }
         }
         String fileName1 = pattern1.substring(0, dotPos1);
         String extension1 = pattern1.substring(dotPos1);
         String fileName2;
         String extension2;
         int dotPos2 = pattern2.indexOf('.');
         if (dotPos2 != -1) {
            fileName2 = pattern2.substring(0, dotPos2);
            extension2 = pattern2.substring(dotPos2);
         }
         else {
            fileName2 = pattern2;
            extension2 = "";
         }
         String fileName = fileName1.endsWith("*") ? fileName2 : fileName1;
         String extension = extension1.startsWith("*") ? extension2 : extension1;

         return fileName + extension;
      }
   }

   /**
    * Given a full path, returns a {@link Comparator} suitable for sorting patterns in order of explicitness.
    * <p>The returned <code>Comparator</code> will {@linkplain java.util.Collections#sort(java.util.List,
    * java.util.Comparator) sort} a list so that more specific patterns (without uri templates or wild cards) come before
    * generic patterns. So given a list with the following patterns: <ol> <li><code>/hotels/new</code></li>
    * <li><code>/hotels/{hotel}</code></li> <li><code>/hotels/*</code></li> </ol> the returned comparator will sort this
    * list so that the order will be as indicated.
    * <p>The full path given as parameter is used to test for exact matches. So when the given path is {@code /hotels/2},
    * the pattern {@code /hotels/2} will be sorted before {@code /hotels/1}.
    * @param path the full path to use for comparison
    * @return a comparator capable of sorting patterns in order of explicitness
    */
   public Comparator<String> getPatternComparator(String path) {
      return new AntPatternComparator(path);
   }


   private static class AntPatternComparator implements Comparator<String> {

      private final String path;

      private AntPatternComparator(String path) {
         this.path = path;
      }

      public int compare(String pattern1, String pattern2) {
         if (pattern1 == null && pattern2 == null) {
            return 0;
         }
         else if (pattern1 == null) {
            return 1;
         }
         else if (pattern2 == null) {
            return -1;
         }
         boolean pattern1EqualsPath = pattern1.equals(path);
         boolean pattern2EqualsPath = pattern2.equals(path);
         if (pattern1EqualsPath && pattern2EqualsPath) {
            return 0;
         }
         else if (pattern1EqualsPath) {
            return -1;
         }
         else if (pattern2EqualsPath) {
            return 1;
         }
         int wildCardCount1 = getWildCardCount(pattern1);
         int wildCardCount2 = getWildCardCount(pattern2);

         int bracketCount1 = StringUtils.countOccurrencesOf(pattern1, "{");
         int bracketCount2 = StringUtils.countOccurrencesOf(pattern2, "{");

         int totalCount1 = wildCardCount1 + bracketCount1;
         int totalCount2 = wildCardCount2 + bracketCount2;

         if (totalCount1 != totalCount2) {
            return totalCount1 - totalCount2;
         }

         int pattern1Length = getPatternLength(pattern1);
         int pattern2Length = getPatternLength(pattern2);

         if (pattern1Length != pattern2Length) {
            return pattern2Length - pattern1Length;
         }

         if (wildCardCount1 < wildCardCount2) {
            return -1;
         }
         else if (wildCardCount2 < wildCardCount1) {
            return 1;
         }

         if (bracketCount1 < bracketCount2) {
            return -1;
         }
         else if (bracketCount2 < bracketCount1) {
            return 1;
         }

         return 0;
      }

      private int getWildCardCount(String pattern) {
         if (pattern.endsWith(".*")) {
            pattern = pattern.substring(0, pattern.length() - 2);
         }
         return StringUtils.countOccurrencesOf(pattern, "*");
      }

      /**
       * Returns the length of the given pattern, where template variables are considered to be 1 long.
       */
      private int getPatternLength(String pattern) {
         Matcher m = VARIABLE_PATTERN.matcher(pattern);
         return m.replaceAll("#").length();
      }
   }

}
